1. Field of the Invention
This invention relates to a method of generating a complex curved surface and, more particularly, to a method of generating a complex curved surface by combining at least two three-dimensional curved surfaces.
2. Description of the Related Art
A curved surface of a three-dimensional metal mold or the like on a design drawing is generally expressed by a plurality of section curves, but no profile data is shown for the shape of the area lying between a certain section curve and the next adjacent section curve. In numerically controlled machining it is essential that machining be carried out so as to smoothly connect these two section curves despite the fact that the profile between them is not given. In other words, this means that machining must be performed by generating the curved surface between the two section curves from such data as that indicative of the section curves, storing on an NC tape the data concerning the generated curved surface, and carrying out machining in accordance with commands from the NC tape. To this end, there has been developed and put into practical use a method comprising generating a plurality of intermediate sections in accordance with predetermined rules using data specifying a three-dimensional curved body, finding a section curve (intermediate section curve) on the curved body based on the intermediate sections, and generating a curved surface of the three-dimensional body based on the plurality of generated intermediate section curves. (For example, see U.S. Pat. No. 4,491,906).
Depending upon machining, there are cases where it is necessary to machine a complex curved surface obtained by combining two or more three-dimensional curved surfaces.
In such complex curved surface creation, it is necessary to specify the complex curved surface by adopting the intersection between three-dimensional curved surfaces as a boundary, using a first curved surface as one side of the complex curved surface, and using a second curved surface as the other side of the complex curved surface.
However, since specifying the intersection is difficult in complex curved surface creation processing of this kind, a complex curved surface cannot be created accurately through simple processing.